Fourteen patients with superficial basal cell carcinomas (BCCs) and fifteen patients with nodular BCCs were investigated by means of laser-induced fluorescence (LIF) in connection with photodynamic therapy (PDT). Topical application of delta-amino levulinic acid (ALA) was performed six hours prior to the treatment session. Fluorescence spectra were recorded, using a point-monitoring system with an excitation wavelength of 405 nm. The measurements were performed in scans over the lesion and the surrounding normal skin before application of ALA, and immediately before and after the laser treatment. The selective uptake of the photosensitiser resulted in a fluorescence intensity ratio of 2.4:1 for superficial BCCs and 2.5:1 for nodular BCCs. If the fluorescence intensity was divided by the autofluorescence, this resulted in a contrast enhancement of about a factor 6 for tumour tissue. In seven patients (five with nodular BCC and two with superficial BCC), additional fluorescence measurements were performed two and four hours following the ALA application, and two hours after the PDT procedure. Thus, the kinetics of the transformation of ACA to protoporphyrin IX (PpIX) could be followed, which indicated that the synthesis of PpIX was more rapid in the tumour than in the normal tissue. After four hours, the PpIX level inside the tumour was saturated, while there still was an accumulation in the surrounding skin. The highest contrast between tumour and normal skin was reached within two hours after the ALA application.

The effects of different parameters of interest for the localization of malignant tumours in situ by means of laser-induced fluorescence and haematoporophyrin derivatives were investigated. Such parameters are drug composition, drug concentration, laser pulse energy and excitation wavelength. In order to assess the relative merits of the tumor tumour-seeking agents Photofrin (haematoporphyrin deriative) and Photofrin II (dihaematoporphyrin ether) we have performed a comparative study on rat tissues. The results suggest that Photofrin is at least as good as the therapeutically more potent agent Photofrin II. A linear relation between drug dose and recorded prophyrin fluorescence intensity was also found. Using not only the porphyrin fluorescence, but also natural tissue autofluorescence, better tumour demarcation is observed when utilizing an excitation wavelength shorter than the porphyrin excitation peak at 405 nm.

Fluorescence spectra from different organs in rats and mice have been recorded to explore the potential of non-intrusive tissue diagnostics. The fluorescence was induced by a nitrogen laser that emitted at a wavelength of 337 nm. Optical multichannel techniques were used for the detection. Spectra are given from 19 different sites in Wistar/Furth rats, including an inoculated malignant tumour. The spectra seem to be a sum of two wavelength distributions only, each distribution occurring with a different weight in different organs. Spectra obtained from living and dead tissue were compared to verify that the measurements on sacrificed experimental animals were valid. Preliminary results are given for some human tumours, transplanted in nude mice, and for some human skin samples.

Diode laser absorption spectroscopy was utilized for non-intrusive assessment of gas content in human body cavities, including intestines and lungs of a new-born, the mastoid bone, and sinus cavities for monitoring sinusitis recovery in adults.

Non-invasive diode laser spectroscopy was, for the first time, used to assess gas content in the intestines and the lungs of a new-born, 4 kg, baby. Two gases, water vapor and oxygen, were studied with two low-power tunable diode lasers, illuminating the surface skin tissue and detecting the diffusely emerging light a few centimeters away. The light, having penetrated into the tissue, had experienced absorption by gas located in the lungs and in the intestines. Very distinct water vapor signals were obtained from the intestines while imprint from oxygen was lacking, as expected. Detectable, but minor, signals of water vapor were also obtained from the lungs, illuminating the armpit area and detecting below the collar bone. Water vapor signals were seen but again oxygen signals were lacking, now due to the difficulties of penetration of the oxygen probing light into the lungs of this full-term baby. Ultra-sound images were obtained both from the lungs and from the stomach of the baby. Based on dimensions and our experimental findings, we conclude, that for early pre-term babies, also oxygen should be detectable in the lungs, in addition to intestine and lung detection of water vapor. The present paper focuses on the studies of the intestines while the lung studies will be covered in a forthcoming paper.